Steam dash-valve



(No Model.) 7

G. G. WORTHINGTON. STEAM DASH VALVE.

No. 561,747. Patented June 9, 1896.

M Q in g a 2- w a 1 5 Q W L l Q k 7 1206/1257 .1 mfliw opposite UNITEDSTATES PATENT OFFICE.

STEAM DASH-VALVE.

SPECIFICATION forming part of Letters Patent No. 561,747,

dated June 9, 1896.

A;:;'-.ez .fiien l d T131; 3, 1895- Serial No. 554,829. (No model.)

struction for direct-acting engines by which a steam-cushion for thepiston, shall be secured at the end of the stroke. The cushion isusually provided by arranging the exhaustport so as to be covered by thepiston as the latter approaches the end of its stroke; but it is foundin practice that this arrangement is not under all conditions certainand sufficientfor the purpose, and provision has some-- times been madefor the admission of a small amount of live steam in front of the pistonjust at the end of the stroke, either on the normal stroke of the pistonor when the piston, through failure of the usual steam-cushion, is notstopped at the normal point. In previous constructions of this classthis live steam has been taken through or from some part outside of thecylinder; but the present invention provides a construction by whichthis steam is taken from the cylinder at the side of the piston, and inthe preferred embodiment of the invention this connection is madethrough the piston, a very simple, compact, and etficient constructionbeing thus provided.

For a full understanding of the invention a detailed description willnow be given of a construction embodying the same in its preferred form,reference being had to the accompanying drawings, forming a part of thespecification, and the features forming the invention specificallypointed out in the claims.

In the drawings, Figure 1 is a central vertical section of a steamcylinrler embodying the invention, the parts being shown on center inthe normal operation of the engine, the valves and trips beingsectioned. Fig. 2 is a similar view showing the parts at the end of thestroke just before the piston stops, with the steam daslrvalves opened,the valves tion may be used for this purpose;

and trips being shown in elevation and section.

A is the steam-cylinder, B the piston, C the steam-chest, D the mainvalve, a the induction-ports, and b the exhaust-ports, of an ordinarydirect-acting engine, all of which parts may be of any suitable formother than that shown.

The piston B is provided with a passage 10 extending through the pistonso as to connect the opposite ends of the cylinder, and this opening isenlarged within the body of the piston, so as to provide valve-seats 1,on which are seated two hollow cylindrical valves 11 12, having ports 2and pressed apart and toward the seats 1 by spring 3, seated within saidvalves, the hollow bodies of the valves preferably overlapping eachother, as shown. The piston may be constructed in any suitable manner toaccommodate the valves, but the construction shown is preferable aspermitting a convenient insertion and removal of the valves, thevalve-chamber and valveseat at one side of the piston being formed by asleeve 13, inserted from the other side of the piston against a shoulder4, formed just inside the body of the piston, and this sleeve 13 beingheld in place by a capli, set into the piston-ring 15 at the oppositeside of the piston before the ring is put on, the cap 14: and ring 15being formed with shoulders 5, holding the cap in place, and thevalvescat 1 at this side of the piston being formed on the cap ll.

The stems (3 of the valves 11 12 may ongage the cylinder-heads; but inthe preferred construction shown an adjustable valve-trip is provided ateach end of the cylinder, so that the amount of dash or cushion may bevaried as required. Any suitable construcbut that shown is simple andeliicient, in which the trip consists of a screw-rod 7, threaded into aplug 16, screwed into the head of the cylinder and packed outside theplug by suitable packing 8, held by a screw-cap 17 on the plug.

The valves and trips will preferably be so constructed and adjusted asto operate at the end of each stroke, thus forming a more effective dashthan the usual cushion and at the same time securing greater economy byfilling the clearance-space with steam of approximately the admissionpressure. They may be arranged, however, so as to come into action onlyas a safety device in case the pis ton passes the point at which it isstopped in the normal operation of the engine. The trips 7 in the lattercase will be adjusted so as not to be engaged by the stems 6 of thevalves 11 12 when the piston is stopped propor] y by the usualsteam-cushion or otherwise, but to actuate one of these valves if thepiston passes this point.

The operation of the construction adjusted to operate at each stroke isas follows: The normal position of the valves 11 12 when there is nopressure in the cylinder and after the pressure on opposite sides of thevalve on the admission side of the piston is equalized is that shown inFig. 1, both valves 11 12 being seated on their respective seats 1 bythe springs 13 and the passage 10 closed. Vhen steam is first admittedand the piston is moving to the right, as indicated by the arrow, thepressure of the live steam behind the piston is suificient to open thevalve 12 against the pressure of spring 3 and admit steam throughopening 10 and ports 2 into the valvechamber formed by the space withinthe valves and behind the valve 11, which is held closed by thispressureand that of spring 3. As soon as the pressure in thisvalve-chamber is equalized with that on the admission side-that is,behind the piston-valve 12 also is closed by the spring 3, and the partsare again in the position shown in Fig. 1. As the piston approaches theend of its stroke the exhaust-port b in advance of the piston is closedby the piston, so as to prevent the escape of steam, and the stem 6 ofvalve 11 engages the trip 7 and is thus pressed backward from its seat 1and opened against the steam and spring pressure behind it, and thepressure in the valve-chamber thus being relieved the valve 12 is thenopened by the steam-pressure behind the piston, and steam passes fromthe rear or admission to the front or exhaust side of the piston andfills the exhaust end 01' the cylinder. The posit-ion of the parts asthe piston approaches the end of the stroke with the valves 11 12 openis shown in Fig. 2. As the piston advances it compresses the steam thusadmitted on the exhaust side, and under this compression of the steamthe steam-pressure on the opposite sides of valve 12 is equalized, andthe valve closes under pressure of the spring 3. Upon reversal of thepiston by shifting the steamvalve D the operation is repeated on theopposite side.

It will be seen that by taking the cushion ing-steam from thesteam-cylinder on the pressure side of the piston a single connec tionmay be used for cushioning at both ends of the cylinder, and a simpleand compact construction be thus provided. It should also be observedthat by utilizing the steam just before it is exhausted from thecylinder to fill the waste clearance-space a decided gain is secured inthe economy of the engine. The temperature of the clearance-wal1s oi thecylinder is raised to a point corresponding to that of the steam on theopposite side of the piston thereby reducing, largely, the conden sationof the fresh steam admitted forthe return stroke. \Vhile it ispreferable that this connection be made through the piston andcontrolled by valves of the form shown, and this construction forms apart of the-invention, it will be understood that the invention is notto be limited to a construction in which connection is made through thepiston nor to the special devices shown, but that modifications maybemade by those skilled in the art without departing from the invention.

That I claim is- 1. The combination with a steam-cylinder and piston, ofa steam rpassage connecting the cylinder it nds on opposite sides of thepiston, a valve mechanism controlling said passage and under a constantpressure less than the steam-pressure on the admission side of thepiston tcndin g to close the passage, and nor mally closing the passageduring the stroke, and means for actuating said mechanism to open thepassage at the desired point in the movement of the piston,substantially as described.

. 2. The combination with a steam-cylinder and piston, of asteam-passage connecting the cylinder ends on opposite sides of thepiston, valves controlling said passage, said valves operatingindependently and opening from the opposite ends of the cylinder andseated by a constant pressure loss than the stea1npressure on theadmission side of the piston, and means for opening the valve on theexhaust side of the piston at the desired point in the movement of thepiston, substantially as described.

3. The combination with a steam-cylinder and pistc i ha. insteam-passage through it, of valves controlling said passage, saidvalves opening from the opposite ends of the cylinder and seated by aconstant pressure loss than the steam-pressure on the admission side ofthe piston, and means for opening the valve on the exhaust side of thepiston at the desired point in the movement of the piston, substantiallyas described.

4:. The combination with a steam-cylinder and piston having asteam-passage through it, of valves controlling said passage, saidvalves operating independently and opening from.

IIO

the opposite ends of the cylinder and seated by a constant pressure lossthan the steampressure on the admission side of the piston, and meansfor opening the valve on the exhaust side of the piston at the desiredpoint in the movement of the piston, substantially as described.

5. The combination with a steam-cylinder and piston having asteanrpassage through it, of valves controlling said passage, saidvalves operating indcpemf ntly and opening 'i'rom the opposite ends ofthe cylinder, and means for opening the valve on the exhaust side of thepiston at the desired point in the movement of the piston, substantiallyas described.

6. The combination with the cylinder A and piston B having steam-passage10, of the valves 11, 12 seated by a spring-pressure less than thesteam-pressure on the admission side of the piston, and means foropening the valve on the exhaust side of the piston at the end of thestroke, substantially as described.

7. The combination with the cylinder A and piston B having steam-passage10, of the valves 11, 12, and spring 3 between said valves and by whichsaid valves are seated having a pressure less than the steam-pressnreonthe admission side of the piston, substantially as described.

8. The combination with the cylinder A and piston B having steam-passage10, of the valves 11, 12, spring 3 between said valves and by which saidvalves are seated having a pressure less than the steam-pressure on theadmission side of the piston, and adjustable valve-trips 7 at each endof the cylinder, substantially as described.

9. The combination with a steam-cylinder and piston, of a steam-passageconnecting the cylinder ends on opposite sides of the piston, a valvemechanism controlling said passage and under a constant pressure lessthan the steam-pressure on the admission side of the piston tending toclose the passage, and normally closing the passage during the stroke,and adjustable means for actuating said valve mechanism to open thepassage whereby the point of the stroke at which the passage is openedcan be varied, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

CHARLES C. WORTHINGTON.

v Witnesses:

LoUIs R. OLBERGER, B. W. PIERSON.

